In the field of acoustic enhancement, a distinction is mainly drawn between enhancement by acoustic insulation and enhancement by acoustic correction.
Acoustic insulation ensures reducing the transmission of sound from one room to another, whether via the floor, the ceiling or the side walls. Acoustic insulation reduces sound of mechanical origin, such as impact or collision sound, and also airborne sound, such as generated by persons speaking or hi-fi systems.
Acoustic correction ensures decreasing the sound in the room where the acoustic source is located. Acoustic correction applies to sound of mechanical origin and airborne sound. In the case of sound of mechanical origin on a floor, this is referred to as acoustic correction of walking sound.
Various acoustic isolating devices are known as underlayers for floor coverings. Mention can be made of the use of cork tiles, of rubber based underlayers, which are in the form of tiles or consist of a leveling screed, or of underlayers based on generally synthetic fibers.
Patent EP 0 413 626 B1 more particularly describes a device for insulation against impact sound. It concerns a soundproofing tile having a hard surface with regard to the covering to be placed, and having an elastic reaction support on the opposite side. It comprises a dense and flexible layer of supercompressed fibers having a density between 60 and 200 kg/m3 which constitutes the elastic reaction support, and a layer of bitumen reinforced with two thin layers of glass fibers anchored respectively in each of the faces of the bitumen layer to constitute the rigid face of this tile, the rigid layer having a thickness of about 5 to 6 mm with a mass per unit area of about 10 kg/m2.
Document FR2517728 proposes the same type of product.
Document US 2005/0214500 also addresses the problem of sound transmission by proposing an underlayer formed of a layer having a certain resilience, between 2 and 10 mm thick and having a density of between 20 and 150 kg/m3, and overlaid by a rigid layer having a modulus of elasticity of between 3 and 18 GPa, and not over 14 mm thick.
Document FR 2 693 221 also proposes a solution for insulation against impact sound, but is in the form of rolls. This underlayer comprises a main layer which is placed on the covering side and a secondary layer which is arranged on the opposite side, the floor side.
The secondary layer of this underlayer provides acoustic attenuation with regard to impact sound due to the very constitution of its cellular material which is elastically deformable. This material is, for example, based on a polymer of the polyvinyl chloride (PVC), polyurethane rubber (PUR), polyethylene (PE), styrene-butadiene rubber (SBR) type, and has a thickness between 0.1 mm and 5 mm, with a density not exceeding 800 kg/m3.
The main layer of the underlayer serves to provide the overall mechanical strength. Its constituent material is, for example, a synthetic polymer such as polyvinyl chloride (PVC), a polypropylene (PP), polyethylene (PE), or a bitumen, but it may also be made from materials of natural origin such as wood fibers. This layer is relatively hard on the surface but remains sufficiently flexible to be rolled so that the underlayer can be provided in the form of rolls.
Document FR2752859 teaches a multilayer material to be placed under a floor covering to reinforce the acoustic insulation against impact zone, and in general to attenuate the propagation of sound waves. This multilayer material, between 3 and 7 mm thick, comprises a first layer facing the floor, consisting of flexible fibrous materials having a mass per unit area of at least 200 g/m2 and which serves to dampen the sound waves, and the second layer facing the covering which is formed of a glass fiber grid or fabric having a mass per unit area of between 300 and 900 g/m2 and which promotes the spreading of the sound waves. A cellular layer of the polyurethane foam type may also be provided, to be placed on the floor opposite the first layer.
It is an object of the invention to provide an alternative solution to the existing solutions for acoustic insulation against impact sound and against airborne sound and, above all, to guarantee an efficient correction of walking sound, while providing great ease of installation.
The figures are not to scale to make them easier to read.